Late summer spiders webs

From my bedroom window this morning, I spotted dozens of large spiders webs being woven in the field behind our house . The interesting thing is that all of them were in a similar stage of construction; the centres were not yet complete.

This suggests that across this large field, all the spiders simultaneously decided that now is the time to start making their webs, and that they all worked at a similar tempo. I could see no web was yet complete and could see only one that was notably behind schedule.